1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device. More particularly, the present invention relates to a method of manufacturing a deep trench capacitor.
2. Description of the Related Art
In a Dynamic random Access Memory (DRAM), the capacitor is the signal storage center. The more electric charges are stored in the capacitor, the less likely it is to be influenced by noise (for example, the soft errors created by particle .alpha.) when retrieving data, and the refresh frequency of the DRAM can also be reduced.
However, when the semiconductor process enters a deep sub-micron manufacturing, the dimensions of the devices are shrunk correspondingly. In light of the former DRAM storage memory structure, it also reflects that the space for accommodating a capacitor is becoming smaller. Therefore, how to maintain the capacitor so that there is ample capacitance becomes an important topic for manufacturing a semiconductor device that is about 0.25 .mu.m and smaller. In order to increase the area of the capacitor, a popular method is provided to increase the capacitance of the capacitor.
The stacked capacitor and the trench-type capacitor are conventionally used to increase the surface area of the capacitor. The stacked capacitor has many different three-dimensional structures such as a crown, fin, cylinder, or a spread, while the trench-type capacitor has different three-dimensional structures such as a deep trench or a buried strap trench. Even if the various structures of the above described capacitors fulfill the requirements of designs for relatively high DRAM density, however, under the limited design rules of the device dimensions, it is very difficult to solely use these structures to manufacture a capacitor of 256 MB or as much as 1 GB DRAM.